1. Field of the Invention
The present invention relates to a resin board which is used as a circuit board, a connection medium body, a manufacturing process for a connection medium body a circuit board and a manufacturing process for a circuit board.
2. Description of the Related Art
In recent years, together with the miniaturization, reduction of weight, increased functionality and increased performance of electronic devices, the demand has become strong, concerning industrial application as well as concerning application in the broad field of consumer devices, for a multi-layer circuit board on which semiconductor chips such as LSIs can be mounted in high density at an inexpensive price.
A resin multi-layer circuit board which can be supplied less expensively than a ceramic multi-layer board and which can fulfill the above described market demand has attracted attention as a substitute for a conventional ceramic multi-layer board and technological development has been carried out to develop a resin multi-layer circuit board that is a board suitable for high density mounting.
As a resin multi-layer circuit board developed in this manner, a circuit board of an any layer inner via hole construction has been disclosed in Japanese Unexamined Patent Publication No. Hei 06-268345 (1994). This circuit board is a resin multi-layer board using a composite material of aramid non-woven fabric reinforcing material and an epoxy resin as the insulating layer and, therefore, can be supplied at a comparatively inexpensive price. In addition, this circuit board adopts the any layer inner via hole construction, that is to say, an interstitial via hole connection construction which can connect arbitrary positions in wiring layers through conductive paste and, therefore, becomes, suitable for high density mounting.
A circuit board of the any layer inner via hole construction having the above characteristics cannot be formed unless a prepreg is used which has voids in the inside due to the impregnation of resin into a non-woven fabric. That is to say, this circuit board has a construction which can be implemented only by using a particular material.
However, in addition to a higher density of mounting, today, market demands have become as follows. That is to say, market demands are manifold and there are demands such as a circuit board of a low dielectric constant suitable for a high speed circuit network, a circuit board of a high heat resistance, and the like. Therefore, it is required to implement a circuit board which has characteristics that fulfill respective desires and suitable for high density mounting.